Add Mistral Vibe as a supported agent

[kojunseo]

I'd like to add Mistral Vibe as a supported coding agent.

I tested Herdr 0.7.4 with Vibe 2.22.0 in a disposable named session. Vibe runs normally today, but Herdr does not recognize it as an agent. Its foreground job is a Python launcher whose script argument is vibe, which fits Herdr's existing wrapped-agent detection once Vibe is registered.

Vibe also exposes stable screen evidence for the states Herdr tracks:

• idle: the Mistral Vibe header, input prompt, and token footer
• working: the generating indicator and Esc/Ctrl+C to interrupt
• blocked: permission choices such as Allow once, Always allow, Deny, and Esc reject, plus the interactive-question UI

My proposed focused scope is:

• register vibe for process detection and herdr agent start --kind vibe
• add a screen manifest for idle, working, permission, and question states
• add process/manifest tests and update docs/next
• keep screen detection authoritative rather than introducing lifecycle-hook state

The feasibility investigation is complete, so if this direction is accepted I can prepare a draft PR right away. I will validate it with the repository checks and live detection-buffer reads, and keep it within the external-contributor intake budget.

Would you be open to this contribution?

[guiand888]

+1 this is absolutely needed!

[hnrkptrsn]

Posting here, but #883 is an almost duplicate.

I've forked herdr and added support for Msitral Vibe - using Mistral Vibe.
Feel free to test the branch, which at first glance seems to work for me.

[MiggiV2]

+1 ^^